drm/i915/gt: Push context state allocation earlier

Allow for knowledgeable users to preallocate the context state, and to
separate the allocation step from the pinning step during
intel_context_pin()
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200109085717.873326-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gt/intel_context.c

@@ -43,24 +43,42 @@ intel_context_create(struct intel_engine_cs *engine)
 	return ce;
 }
 
-int __intel_context_do_pin(struct intel_context *ce)
+int intel_context_alloc_state(struct intel_context *ce)
 {
-	int err;
+	int err = 0;
 
 	if (mutex_lock_interruptible(&ce->pin_mutex))
 		return -EINTR;
 
-	if (likely(!atomic_read(&ce->pin_count))) {
-		intel_wakeref_t wakeref;
-
-		if (unlikely(!test_bit(CONTEXT_ALLOC_BIT, &ce->flags))) {
+	if (!test_bit(CONTEXT_ALLOC_BIT, &ce->flags)) {
 		err = ce->ops->alloc(ce);
 		if (unlikely(err))
-				goto err;
+			goto unlock;
+
+		set_bit(CONTEXT_ALLOC_BIT, &ce->flags);
+	}
+
+unlock:
+	mutex_unlock(&ce->pin_mutex);
+	return err;
+}
 
-			__set_bit(CONTEXT_ALLOC_BIT, &ce->flags);
+int __intel_context_do_pin(struct intel_context *ce)
+{
+	int err;
+
+	if (unlikely(!test_bit(CONTEXT_ALLOC_BIT, &ce->flags))) {
+		err = intel_context_alloc_state(ce);
+		if (err)
+			return err;
 	}
 
+	if (mutex_lock_interruptible(&ce->pin_mutex))
+		return -EINTR;
+
+	if (likely(!atomic_read(&ce->pin_count))) {
+		intel_wakeref_t wakeref;
+
 		err = 0;
 		with_intel_runtime_pm(ce->engine->uncore->rpm, wakeref)
 			err = ce->ops->pin(ce);

drivers/gpu/drm/i915/gt/intel_context.h

@@ -31,6 +31,8 @@ void intel_context_fini(struct intel_context *ce);
 struct intel_context *
 intel_context_create(struct intel_engine_cs *engine);
 
+int intel_context_alloc_state(struct intel_context *ce);
+
 void intel_context_free(struct intel_context *ce);
 
 /**